500 Servlet Exception

java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
	at java.util.ArrayList.RangeCheck(ArrayList.java:546)
	at java.util.ArrayList.get(ArrayList.java:321)
	at com.yysoft.stat.StatManager.getUserAgent(StatManager.java:376)
	at com.yysoft.stat.StatManager.addStat(StatManager.java:87)
	at com.yysoft.stat.StatManager.stat(StatManager.java:64)
	at _english._index__jsp._jspService(/web/system/stat/catalogstat.jsp:2)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
	at com.caucho.jsp.Page.subservice(Page.java:485)
	at com.caucho.server.http.FilterChainPage.doFilter(FilterChainPage.java:182)
	at com.caucho.server.http.Invocation.service(Invocation.java:311)
	at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
	at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:221)
	at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:163)
	at com.caucho.server.TcpConnection.run(TcpConnection.java:137)
	at java.lang.Thread.run(Thread.java:595)